sage: # Example 2 - Page 405
sage: a = vector([4,0,1])
sage: b = vector([2,-5,1/3])

sage: print -a
(-4, 0, -1)

sage: print 7 * a
(28, 0, 7)

sage: print a + b
(6, -5, 4/3)

sage: print 2 * (a - b)
(4, 10, 4/3)

sage: print 2 * a - 2 * b
(4, 10, 4/3)